I--------,
I.
Determination of Aldehydes from Equilibria Shifts C, Aldehyde in CN
Table
Oxo Alcohol, Grams/Liter
Taken 1.90 2.84 4.59 6.57 9.06 11.8 15.1
Found 2.07 2.90 4.78 6.74 9.35 12.4 15.5
%
+8.9
tion of aldehydes
I
-__
+4.1 +2.5
+3.2 +5.1 +2.7
b = cell path, cm. Determine the change in a b r p t i v i t y , Au,resulting from the equilibrium shift.
- g l 0 c.
To determine the unknown aldehyde concentration, repeat the determination of a b r b a n c e a t 25" and 100° C. using the sample solution. Then Amo 0.
- AlO
'
ALCOI(OLd
+2.1
e = concentration, gram liter
e =
I
Error,
L-DISPOSAL
peak was masked by the addition of a
& = amoc.
~
C.
Aa
The method was tested on a number of decyl aldehyde solutions. Absorbance measurements were made a t room temperature and sgsin at loOo C. In all cases the characteristic carbonyl
phenol inhibitor. A typical absorption curve is shown in Figure 4. The experimental results are tabulated in Table I. The s o w for the positive bii was not determined but is probably due to a shift with temperature of the inhibitor absorption maximum. APPUCATION TO PROCESS STREAM ANALYSIS
Estimating the carbonyl contents of an alcohol solution by measurement of the ultraviolet absorbance at two temperatures is particularly applicable to process stream analysis. The sample stream is divided into two p a r k and passed through separate cells of an ultraviolet analyzer. The cells are thermostated at substantially dXerent temperatures. A null-balance system continuously monitom the absorbance difFerence between the two cells. A
schematic representation of such a system is shown in Figure 5. As the technique is insensitive to the presence of extraneous absorbers, high spectral resolution is unnecessary. LITERATURE CITED
J . Am Chem. soc. 50,499 (1928). (2) Ashdown, A., Klete, T. A., Ibid., 80, 1454 (1958). (3) &
